(a) Technical Field
The present disclosure relates to an engine mount for a vehicle and more particularly, to a semi-active engine mount for a vehicle capable of improving noise, vibration, and harshness (NVH) performance and ride quality by decreasing dynamic characteristics of the mount when the vehicle idles and increasing a loss factor during the driving operation of the vehicle.
(b) Background Art
Generally, an engine mount prevents vibration of an engine from being transmitted to a vehicle body, insulates a vibration mode of a vehicle and control motion of the engine. The engine mount minimizes motion of the engine by making the engine mount hard statically and insulates the high-frequency vibration by making the engine mount soft dynamically.
Usually, the engine mount formed from a rubber material has a drawback of being vulnerable to low-frequency and large-displacement vibration. Accordingly, the engine mount cannot sufficiently satisfy both high-frequency and low-amplitude vibration and low-frequency and large-displacement vibration. Therefore, a fluid engine mount has been used which may absorb and attenuate vibration over a widespread region that includes the high-frequency and low-amplitude vibration and the low-frequency and large-displacement vibration input to the engine mount when the engine operates.
Recently, improved noise reducing properties of a vehicle for a driver and improved NVH performance associated with a noise problem has been required. In particular, engine mounts with various control methods have been developed. For example, a hydraulic mount, a semi-active mount, and the like, which prevent deterioration in NVH performance of a variable cylinder engine have been developed to improve fuel economy of the vehicle.
Further, to improve NVH performance, insulation performance is increased by decreasing the dynamic characteristics of the mount when the vehicle idles and to improve ride quality by increasing a loss factor during the driving operation of the vehicle. However, due to of the nature of the current hydraulic mount, a loss factor tends to decrease when dynamic characteristics decrease and the dynamic characteristics tend to increase when the loss factor increases. Accordingly, the loss factor and the dynamic characteristics conflict with each other.
A semi-active mount (switchable mount) has been developed. In particular, the semi-active mount decreases dynamic characteristics when the vehicle idles and increases a loss factor during the driving operation of the vehicle. Accordingly, the semi-active mount is widely and progressively applied to many vehicles. However, when the current semi-active mount, a coil having high capacity that corresponds to rigidity of a rubber spring needs to be applied, costs and weights are greatly increased due to a number of components being required and a structure thereof is being complex. The current semi-active mount is disadvantageous in terms of packaging due to a size greater than that of the existing hydraulic mount.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.